Archives quotidiennes :

Sixty-six million years ago, the world burned. An asteroid crashed to Earth with a force one million times larger than the largest atomic bomb, causing the extinction of the dinosaurs. But dinosaurs weren’t the only ones that got hit hard — in a new study, scientists learned that the planet’s forests were decimated, leading to the extinction of tree-dwelling birds.

A highly precise method to determine past typhoon occurrences from giant clam shells has been developed, with the hope of using this method to predict future cyclone activity.

A team of researchers led by Tsuyoshi Watanabe of Hokkaido University has discovered that giant clams record short-term environmental changes, such as those caused by typhoons, in their shells. Analyzing the shell’s microstructure and chemical composition could reveal data about typhoons that occurred before written records were available… (…)

The whole Tridacna maxima valve. The shell was cut in two sections along the maximum growth axis.

Scientists claim that the ocean’s global mean surface pH may have declined (i.e., became less alkaline and thus more “acidic”) by -0.08 in the last 265 years — from 8.13 during pre-industrial times to 8.05 today. That’s an overall, long-term pH change rate of -0.0003 per year.

By way of comparison, from one season to the next, or over the course of less than a year, pH levels naturally change by twice that amount (±0.15 pH units). On a per-decade scale, oceanic pH can naturally fluctuate up and down by up to 0.6 units within a span of a decade (as shown in red below).